1. Field of the Invention
The present invention relates to an up-drawing continuous casting apparatus and an up-drawing continuous casting method.
2. Description of Related Art
Japanese Patent Application Publication No. 2012-61518 (JP 2012-61518 A) proposes a free casting method as an epoch-making up-drawing continuous casting method that does not require a mold. As described in JP 2012-61518 A, when a starter is immersed into a surface of molten metal (that is, a molten metal surface) and then the starter is drawn up, the molten metal is also led out following the starter due to a surface film and a surface tension of the molten metal. Here, a casting having a desired sectional shape can be continuously casted by leading out the molten metal via a shape determining member placed near the molten metal surface, and then cooling the molten metal thus led out.
With a normal continuous casting method, the sectional shape and the shape in a longitudinal direction are both determined by a mold. Particularly, in the continuous casting method, solidified metal (i.e., a casting) should pass through a mold, so that a casting casted hereby has a shape that extends linearly in the longitudinal direction. In the meantime, the shape determining member in the free casting method determines only the sectional shape of the casting and does not determine the longitudinal shape thereof. On that account, castings having various longitudinal shapes can be obtained by drawing up the starter while moving the starter (or the shape determining member) horizontally. For example, JP 2012-61518 A describes a hollow casting (that is, a pipe) formed not in a linear shape in its longitudinal direction, but in a zigzag shape or a helical shape in the longitudinal direction. Here, a free casting apparatus described in JP 2012-61518 A can change the sectional shape of the casting by moving the shape determining member.
The inventor(s) found the following problem. JP 2012-61518 A describes that the sectional shape of the casting is changed by moving the shape determining member as described above, but does not describe how the shape determining member is moved at that time. If the shape determining member is deformed so that some parts of the shape determining member are distanced from each other, the sectional shape of the casting cannot be determined in that distanced part. Further, even if a plurality of shape determining members is put on top of one another in advance and the plurality of shape determining members is moved relative to each other within a range where they are put on top of one another, there is a possibility that their moving ranges are limited. That is, the free casting method described in JP 2012-61518 A has a possibility that a degree of freedom of the sectional shape of the casting cannot be improved.